Mass Flow Controller Model-Based Control
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Solution Overview
Problem
Current mass flow controllers, relying on PID-based control, face limitations in responding quickly to changing conditions and require extensive tuning for each specific application, making them inadequate for modern semiconductor processes that demand fast response times and immunity to perturbations.
Innovation Solution
A model-based control system for mass flow controllers that utilizes mathematical models of components like sensors, valves, and controllers to tailor the control scheme to specific applications, enabling automatic optimal response without the need for extensive tuning, using models such as valve flow, force versus lift, and hysteresis models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If PID-based control is used in mass flow controllers, then the control system is simple to implement, but the response time is slow and extensive tuning is required for each application
Solution Approach 1:
The patent pre-characterizes the flow meter and valve components during manufacturing to create lookup tables that map control signals to actual flow rates and valve positions. This preliminary characterization eliminates the need for extensive field tuning and enables fast response by directly querying pre-computed values rather than performing complex real-time calculations.
Solution Approach 2:
The patent replaces traditional PID control algorithms with a lookup table-based control system that uses pre-characterized component data. This substitution eliminates the need for complex mathematical computations and iterative tuning, providing faster response times while reducing computational complexity.
2Adaptability or versatility
If PID-based control is used in mass flow controllers, then the control algorithm is simple, but extensive tuning is required for each specific application and condition
Solution Approach 1:
The system performs comprehensive characterization of flow meters and valves during manufacturing, creating lookup tables that capture component behavior across all operating conditions. This preliminary action ensures the system is immediately adaptable to different applications without requiring time-consuming field tuning.
Solution Approach 2:
The control system automatically selects appropriate lookup tables and parameters based on the specific application and operating conditions, eliminating the need for manual tuning by operators. The system self-configures by querying pre-stored characterization data corresponding to the installed components and process requirements.
3Adaptability or versatility
If complex algorithms are used to adjust P, I and D parameters, then the control system can adapt to changing conditions, but the device complexity increases
Solution Approach 1:
The patent replaces complex adaptive algorithms with pre-characterized lookup tables that inherently capture component behavior across all operating conditions. The system achieves adaptability by querying the appropriate pre-computed data based on current conditions rather than performing complex real-time calculations or iterative parameter adjustments.
Solution Approach 2:
Complex adaptive behavior is pre-computed during manufacturing and stored in lookup tables. This preliminary action transfers the computational complexity from runtime operation to manufacturing characterization, enabling simple and fast runtime control while maintaining high adaptability to changing conditions.
Data Source
AI summary
The disclosed embodiments include a method, apparatus, and computer program product for controlling the mass flow rate of a fluid. For example, the disclosed embodiments include a method and a mass flow controller configured to determine, using on valve hysteresis model, a valve drive necessary to generate a force to achieve a valve lift for moving an adjustable valve to a desired valve position based on a given flow setpoint for controlling the flow of a fluid.